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Dynamic spectrum access, enabled by cognitive radio technologies, has become a promising approach to improve efficiency in spectrum utilization, and the spectrum auction is one approach in which unlicensed wireless users lease some unused bands from spectrum license holders. However, spectrum auctions are different from traditional auctions studied by economists, because spectrum resources are interference-limited...
In this paper, the gain and noise performances of a DC-6 GHz microwave amplifier using commercial Silicon Germanium Heterostructure Bipolar Transistor (SiGe HBT) are investigated at different bath temperatures. At room temperature, the two-stage amplifier has a gain of 21 dB and a noise figure of 3.7 dB at 2.62 GHz. When cooled to 70 K, it demonstrates 27 dB gain and 1.5 dB noise figure at the same...
In this paper, we present the results of identification and control experiments on NASA's ACES structure at the Marshall Space Flight Center. The models used for controller design were obtained from identification experiments employing the algorithm Q-Markov Cover. The OVC algorithm used for control design produces a controller minimizing the control energy of the closed-loop system, subject to inequality...
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